Delayed Rejection
by Taivasalla
Summary: When Rin transplanted a bloodline limit on the battlefield, it was an unprecedented advance in shinobi medical jutsu. But years later, Rin is dead, and Kakashi's body is rejecting the sharingan eye. He is left with a terrible choice: remove Obito's eye, or risk it killing him. 1-shot.


_A/N: obviously all the medical mumbo-jumbo is nonsense. they're magical ninja doctors. fun real fact: the only transplantable part of the eye is the cornea! (but we're working on getting to whole eyes)_

* * *

The medic who performed the mandatory post-action physical started with the basics. Blood pressure slightly elevated; not enough to cause concern. Heart rate normal. Temperature high. He inspected the field stitches closing a gash on the shinobi's arm, and pronounced them competent and uninfected. The jounin's only other injuries were mild bruising; he'd come out relatively unscathed from what the abbreviated mission report had called a "multiple engagement mid-length assignment." The medic recorded core chakra levels, and checked the shinobi's ears and throat. Then he asked the man to take off the hitai-ate covering his left eye.

Kakashi took it off, folded it carefully over his knee, and opened his eyelid. The medic hesitated. "Is that normal, Hatake-san?"

"No," Kakashi said, deadpan.

The young medic swallowed. "I need to call in a consult, Hatake-san. If you wouldn't mind waiting a moment…"

* * *

"How long has it been like that?" The doctor peeled back Kakashi's eyelid, flashed a light into his pupil.

Black sparks flitted across Kakashi's vision, over and around the grey spot that had floated in his sight the past day. The ache turned into a red-hot spike driving through his eye socket and into his brain. "Three days." Kakashi rubbed delicately at the wetness on his cheek.

"Has there been any recent trauma to your eye?"

"No."

The doctor leaned back. Redness that had nothing to do with the sharingan had crept into the white of the eye. The skin around it was puffy and peeling, a scalded pink. "Are you in pain?"

"Yes," Kakashi said.

"On a scale of one to ten, how badly does it hurt?"

Kakashi considered that. Remembered the feeling of being stabbed in the kidney with a serrated blade. Remembered being dragged across churned dirt, an exhausted and distracted battlefield medic healing the wound while explosions shook the ground under them. Compared that to the nail currently being driven into his eyeball by a demon blacksmith. "Four."

The doctor's lips twitched down, as if he were suppressing a career's worth of exasperation at damaged ninja. "I'm calling Ozawa-sensei. A nurse will come and take some blood. Don't give him any trouble." With that admonishment, the doctor swept out.

* * *

Ozawa-sensei shone a light in his eyes, flicking back and forth between the red and the grey. She prodded the skin around his eye socket with gloved hands. She ordered his shirt off, and inspected the seals inked on his back. She held a diagnostic jutsu over his face, then pressed a chakra meter to each temple and to the base of his spine. She asked him the same questions the first doctor had, and a dozen more. When she had finished her inspection, she flipped through his medical file at the counter across the room. Kakashi waited out the silence, sharingan closed.

When she spoke, Ozawa-sensei was calm, matter of fact. "I need the blood tests to be sure, but it looks like the original anti-rejection seals have failed, and your body is violently rejecting the transplanted eye." She paused, giving him time to respond. Kakashi said nothing, just blinked his own eye and waited.

"You have two options. We can attempt to heal the damage already done and apply new anti-rejection seals. There's no guarantee that will work; once the body begins to reject a transplanted organ, it can be difficult to stabilize it again. Beyond that, the eye is already leaking chakra into your cranial paths. I know we've talked about leakage as a danger before; you do remember the consequences?"

Kakashi nodded.

Ozawa listed them anyway. "Headaches, reduced stamina, blindness, brain damage. You're already having the headaches." She tapped the skin at the edge of her own eye socket. "The peeling and redness here is mild chakra poisoning. The longer we spend trying to salvage the transplant, the higher your risk for serious damage gets.

"But you might get to keep the eye. The second option is we remove the eye. It's a relatively simple surgery, and we can do it immediately. The current damage can be healed, and it won't get any worse. You'll lose left-side vision permanently, but you're already practiced at compensating; it won't end your career."

She stood up. "I'll give you some time to think about it, but whichever you choose, we need to start soon."

"Save the eye." Kakashi said it without hesitation.

"Hatake," Ozawa began, "It's a big decision, take some time."

Kakashi met her eyes firmly. "I made this decision years ago, sensei."

"Decisions can change, Hatake." He said nothing, just held her gaze with that half-lidded grey eye, circled in exhausted darkness. Ozawa sighed. "You teammate didn't give you that eye to kill you."

He looked away. "Save the eye, Ozawa-sensei," he said quietly. "Please."

* * *

Ozawa reduced the swelling before she left. An orderly came to move Kakashi out of the exam rooms, to a room with two beds and a window looking out over a small courtyard. In the other bed, an older man slept, bandages across half his face.

A half hour later, Ozawa returned with a Hyuuga chakra specialist. The Hyuuga pressed fingers to Kakashi's temple, and around his eyes. They stepped out of the room to consult. When they came back in, Ozawa painted black seals around Kakashi's eye. Days of tension he hadn't noticed was there drained out of Kakashi's shoulders with the surcease of pain.

"This is a stopgap to the chakra leakage. That's all we can do for now. Hiramitsu-sensei — you remember him? — is coming in to go over Rin-san's notes with me. I'll let you know when we're ready to start. If anything gets worse — pain, vision, headaches — call for a nurse. Understand?"

"Yes, sensei," Kakashi agreed. He might deny injuries and sneak out of the hospital and keep taking missions until he dropped — but he wouldn't risk Obito's eye. He would obey.

* * *

"We really should be removing the eye," Hiramitsu said, rubbing a hand over his face. Papers covered every surface in Ozawa's office, annotated seal diagrams, scrolls in Rin's delicate, precise handwriting, books on bloodline limits opened to pages on doujutsu and limit suppression.

Ozawa shook her head, leaning back in her chair. "He won't let us."

"His reputation isn't worth dying for," Hiramitsu said sharply. "That eye is going to kill him, if not tonight, then in a year or five."

"It's not his reputation he's worried about losing," Ozawa said. She pinched the bridge of her nose and closed her eyes. They'd been at this for hours. "The eye is all he has left of his dead genin teammate. And it's all he has left of Rin."

Hiramitsu took that in silence.

Sounding like she was trying to encourage herself, Ozawa said, "Rin managed to transplant an eye in the middle of a battlefield, with a viable bloodline limit. We should be able to figure this out."

Hiramitsu shut the book in front of him. "Rin is dead," he said, a shadow of pain in his eyes. "And there's no way she could have predicted everything that would go wrong with a bloodline limit transplant. This is not a simple antigen response that we know how to deal with." He took a deep breath. "But let's see if we can give him another five years."

* * *

Kakashi put down his book when the three doctors came into the room. Hiramitsu leaned up against the wall by the door, arms crossed. The Hyuuga sat down in the visitor's chair and stared out the window. Ozawa stood by Kakashi's bed, and folded her hands in front of her. "We have a plan," she said. "It's going to take two separate procedures, and we need to start the first one within the hour. We can't guarantee this will work, Hatake. And if it does, it may not be permanent. We could see a negative reaction a few months down the road, or a few years. Do you still want to proceed?"

Kakashi nodded.

"The first thing we need to do is heal the existing damage in the eyeball and the surrounding tissues. You've got a retinal bleed — that's the spot you've been seeing. Your immune system has been eating away at the eye, and the sharingan has been dumping chakra into your head. We'll fix the damage, then fine-tune the antigen masking seals. Rin didn't have the time or equipment to do a full typing on either of your tissues, so she went scorched-earth on everything; we want to let your body handle as much as possible. And finally, the localized immunosupression seals are nearly burned out, so we'll renew those.

"These are all relatively standard procedures. We'll do them first, tonight."

"Alright," Kakashi said.

"We'll wait a day for those to stablilize," Hiramitsu said, from the wall. "Your pathways are fragile right now, and we can't do too much at once. Fixing the antigen masks and immunosupressors should stop any more immediate damage to the eye."

"I want you here, under observation, tomorrow. We'll keep any swelling down and watch for changes or bad reactions. The day after tomorrow," Ozawa went on, "we need to address the chakra problem."

Hiramitsu took over again. "We are going to place an elemental scrubber and a transformer at the back of your eye. We think part of the reason for the sudden failure was the elemental mismatch between your lightning nature and the eye's fire. We also need to put a pressure lock between the eye and your cerebral coils."

"Why?" Kakashi looked up from the edge of the blanket he'd been folding between his fingertips.

"So you don't fry your brain," Hiramitsu said. At Ozawa's sharp look, he softened his tone. "Look, Hatake, it's not just the creepy red eye that makes up the Uchiha bloodline. Your chakra system isn't adapted to the power of the sharingan. When you use certain high-power aspects of the limit, the chakra backwashes from the eye into your cerebral coils. You're not built for that. Where an Uchiha's coils will stretch and shunt that extra power back to their core, yours leak."

"A lock will stop me from using the eye," Kakashi said.

"Yes, that's the point." Hiramitsu lifted a sardonic eyebrow. "But it only activates when the pressure hits dangerous levels."

"Suddenly not being able to use the eye in combat is dangerous," Kakashi said, equally deadpan. "I'll take a slow frying over a sword in the throat."

Ozawa cut in. "You can make a decision tomorrow. Right now we need to get the basics done before we lose the eye entirely. Are you good with what we're doing tonight? Basic healing, antigen masks, and local immune system supression seals?"

"Yes," Kakashi said. "But not the lock."

Hiramitsu opened his mouth, and Ozawa cut him off with a sharp gesture. "Then lets get you prepped."

* * *

He had a fever the next day that kept climbing. Ozawa put off the second procedure. Hiramitsu came by to check the seal stability, and to call him seven kinds of fool. Then he asked if anyone had been by to visit.

Kakashi, who had not put down his book when Hiramitsu showed up, kept reading.

The next day, Gai showed up. "Your doctor kindly informed me you were here," he said brightly. "I brought you flowers."

What Gai had brought was a single giant sunflower in a comically undersized vase. "Are you using jutsu to keep that from falling over?"

With a blinding grin, Gai lifted up the vase and showed him the sealing tag stuck to the underside. "How are you feeling?"

Kakashi glanced over the top of his book. "Ever been kicked in the face by a horse?"

"It is my good fortune that I have not."

"Go try it and then you'll know."

"I will simply accept that you are in a great deal of pain," Gai said placidly. He sat down in the visitor's chair. "The doctor did not tell me what was wrong, but from the gauze over your eye and the fact that it was the estimable Hiramitsu-sensei who sent the message to me, I assume the sharingan?"

"You should become a detective," Kakashi said. "Give up ninja-ing and move to the capital. Solve crimes and woo beautiful women. Drink too much shochu. Never turn the lights on in your sixth floor apartment. Narrate your daily life. Save the daimyo's life."

"I am more than capable of doing the latter in my current line of work. None of the rest sounds particularly admirable, Kakashi. Except possibly solving crimes and wooing."

"Oh shut up."

The skin by Gai's eyes crinkled as he fought down a smile.

* * *

"No lock."

Ozawa nodded. "Alright."

Hiramitsu scowled, but the argument was over.

It all should only take two hours. They were essentially burning a seal array into the back of the sclera, around the exit of the optic nerve, where the main chakra channel to the eye ran. Hiramitsu inked the array on Hatake's forehead. Ozawa added seals around his eyes and trailing down his temples. As they engaged, the sharingan faded from blood red to black.

Then Hyuuga took over, to do the main work of transferring the seal array permanently into Hatake's head. Halfway through, the sharingan flared to life. His gaze focused deep inside Kakashi's head, Hyuuga saw the sudden rush of chakra that shattered Ozawa's seals as it happened. He slapped a hand over Kakashi's eye as it snapped open. "The sharingan is active," he said calmly.

Hiramitsu swore.

"I'm still holding the working open," Hyuuga said. "If one of you could shut down the sharingan and sedate Hatake again, I can continue."

Ozawa dipped brush into ink and stepped up beside the table. Hiramitsu put a hand on either side of Kakashi's head and pulsed chakra. Kakashi went limp. But Ozawa's seals wouldn't hold. They writhed around Kakashi's eye, darkening and fading until the ink ran and smudged.

The three looked at each other, the Hyuuga's hand still clamped over Kakashi's eye. "Well this is bad," Hiramitsu said.

Grimly, Ozawa dipped her brush in the surgical ink once more. "We can do this."

* * *

Washing ink off his hands in the prep sink, Hiramitsu turned to Ozawa. "I think we'll get a paper out of this one."

Ozawa, leaning against the wall with her eyes closed, chuckled. "Right now, I'd rather have a week of paid leave."

"I'm serious," Hiramitsu said. "We need to get this documented and published. Whole eye transplants are still rare, and bloodline transplants nearly unheard of. That we successfully stabilized a tissue-discrepant transplant with an elemental mismatch—"

"It'll immediately be classified," Ozawa interrupted. "The Uchiha won't want this public."

Hiramitsu shrugged. "Still—"

Ozawa groaned. "I should have gotten Yaginuma to do the seal consult instead of you. You just want to make more work for me."

Shaking water from his hands, Hiramitsu headed for the door. "Obviously my only goal in life. Fine — you can have an hour to revel in the medical breakthrough that happened here today. And then we start drafting."

* * *

Kakashi woke up in darkness. He heard the rapid beeping of a heart rate monitor, in time with the pulsing of blood under his skin. His head hurt, his face hurt. Soft cloth wrapped around both eyes, and he couldn't open the lids.

"You're not blind," a familiar voice said. "You've still got both your eyes, and they both work."

He reached for the bandages over his eyes with shaking hands. Long, calloused fingers wrapped around his and pulled them down. "Not yet."

"When?"

"Ozawa-sensei will come and check on you later today. She'll decide if it's time."

"So what are you doing here?"

"We didn't think it would be good for you to wake up alone in darkness," Kurenai said matter-of-factly.

"We?"

"Oh, you know. Your friends. Raidou is coming by in an hour or so."

"Are you staying?"

"If you want me to."

"Will you read to me?"

"I'll read _my_ book to you. It's a history of Wind Country through the last six centuries."

Kakashi groaned. He let his arm flop down on his face, hiding the shift of fabric as he smiled.


End file.
